The present invention relates to a specific roof-ceiling construction of the original conception and shape. The technical problem that is to be solved by this application is assembling method of constructing roofs with flat soffit over extremely large spans (more than 50 m) whereby the roof-ceiling construction solves both the roof and the finished flat soffit simultaneously. In practice, roof constructions over extremely large spans are mostly unique constructions carried out on special projects and usually constructed completely on the site.
The technical problem of this invention, if defined as a task, is to find out an assembling method of constructing roof-ceiling constructions over extremely large spans, suitable for serial pre-fabrication, as an alternative to customary practice of constructing unique constructions.
The technical problem that is to be solved is to divide the huge construction, unsuitable for transport and handling, into plurality of small assemblies that can be prefabricated and transported and assembled on site into the extremely large-span construction unit with flat soffit. As a part of the present invention some partial technical problems are to be solved such as; forming the light assembly-able soffit, lateral stabilization of the upper longitudinal girder over a large span without increasing its mass through increasing its lateral dimensions, longitudinal and transversal interconnecting of the assembly elements into the entirety. All the other solutions that are part of this invention are related to the practical use of the construction itself, including the advantages described in HR-P20000906A that these constructions offer when compared to other customary roof and ceiling constructions.
The present invention includes the basic concept of the construction and prestressing principles disclosed in U.S. Pat. No. 6,966,159under the name “doubly prestressed composite roof-ceiling constructions”. The just-mentioned patent discloses constructions with flat plate-soffit over mostly used big spans up to 30 m. Such constructions with full-plate-ceilings are not suitable for spans bigger than 30 m because at spans larger than that the full-plate soffit becomes too weighty what modifies many assumptions which are the basis of the work of the construction at smaller spans making this construction inapplicable. For instance, the distinctly thin full plate, at spans up to 30 m, has the overall depth of 5 cm what provides enough depth for anchoring interconnecting bars into the soffit plate concrete to ensure them from pooling-out. The full, thin soffit-plate, if applied at large spans, requires an increment of depth because its connection to the upper longitudinal construction near supports become too weak to bear significant amount of shear. However, at very large spans the soffit plate should have an increased depth that would increase its self-weight and change the concept of its working mechanism based on the light soffit which deflects upwards due to rotation of ends of the construction. Moreover, constructions with full-plate soffit and a span over 50 m would be too long for transport and there would appear a problem of interconnecting smaller assemblies into the soffit plate entirety. Even if possible, carrying-out of such constructions would require pre-tensioning and concreting in site that may be uneconomic.
The present invention relates to a construction that is similar to the construction described in U.S. Pat. No. 6,966,159 and solves its applicability to extremely large spans, allows prefabrication of smaller assemblies that are assembled on site into the entirety and provides the assembling soffit formed by inserting light-plates into the openings of the grid-soffit reducing the weight of the entire construction before being hoisted.
No other similar constructions with flat soffit, except abovementioned ones are known to me.